1. Field of the Invention
The invention relates to an end closure for the nozzle orifice of a dispensing cartridge for multi-component systems, the end closure having at least two parallel stoppers that project from a common base and fit into the adjacent dispensing canals of the nozzle tube of the cartridge.
2. Prior art
An end closure of a similar kind is already known, for example from U.S. Patent Specification No. 3 828 980, which concerns a cartridge made with a sealed nozzle orifice that remains closed when the cartridge is being distributed and stored. The tip of the nozzle of the cartridge is cut off only to open the dispensing canals and enable the contents of the cartridge to be used. The simply designed end closure is used only to close the nozzle temporarily for a short time when the cartridge is partly empty. A further end closure of a similar type is known from European Patent Application published as number 0 261 466. When such a closure is used for a cartridge made with open dispensing canals, it has to be inserted immediately after the cartridge has been filled and must then close reliably and tightly during storage and transport of the cartridge until its contents are applied by the end user. To ensure that the closure does not become loose due to shock, compression of the cartridge's contents, temperature changes, etc, such as often occur during storage or transport, considerable pressure would have to be applied to fit its stoppers in the dispensing canals, but this would considerably complicate insertion of the closure and particularly its removal by the user. Further, because the cross-section of the dispensing canals is often not circular and sometimes has a number of corners, it is not easy to ensure an accurate fit between the cross-section of the canal and that of the stopper.
Instead of end closures with stoppers that project into the dispensing canals, cap closures without such stoppers are also used; these are made either as screw caps or for bayonet-type attachment. In these cases the seal is formed against the flat front face of the nozzle tube into which the dispensing canals discharge adjacent to each other. In the case of two-component or multi-component dispensing cartridges with two or more dispensing canals, the cap closure must contain an elastic sealing insert which the closure presses tightly against the nozzle orifice, because the sealing insert must reliably ensure that the separately stored component materials in the closely adjacent dispensing canals of the cartridge are prevented from coming into contact with each other when they reach the said sealing surface. When delivery pistons are being inserted in the filled cylinders of the cartridge, considerable pressure--which may vary from one cylinder to another may occur and be applied to the component materials, with the risk that component material may leak from one dispensing canal into another. Also, the manufacture and assembly of such sealing inserts cause additional costs, which are of some importance in such a cheap disposable component. Further, it is often difficult to find a material for use as a sealing insert that remains permanently elastic without fatigue but at the same time is equally resistant to all the component materials stored in the cartridge, some of which may be chemically reactive.